The invention relates to cotton harvesters, but more particularly, the invention relates to cotton pickers with rotary doffers.
Prior art cotton picker units use a plurality of coaxially spaced doffers having a plurality of radially aligned annular teeth to doff cotton from a plurality of coordinated barbed spindles. The arrangement and operation of the picking unit with doffers and spindles are well presented in the John Deere Publication A-29-74-2 entitled "Cotton Pickers and Strippers." The prior art doffer consists of a metallic backing plate or disk to which is adhesively bonded on one side a plurality of radially aligned, annular teeth of integrally molded rubber. The backing plate extends to a point well beyond the diameter which corresponds to the mid point of the annular teeth and substantially inhibits deflection of the teeth and doffer rim in an axial direction. Accordingly, the teeth of the doffer are free to deflect only generally circumferentially when cotton or other associated matter is doffed from the coordinated spindles. Should associated matter such as rocks, dirt or plant stock be carried to the doffer by the spindles, there is a strong likelihood that the teeth will quickly abrade or that spindles will break because of limited, if any, deflection afforded the doffer by the backing plate.
Another problem associated with prior art doffers is that the backing plates must be prepared on at least one surface to adhesively bond them to the rubber during molding and curing. The adhesive bond is subject to early failure which may render a picker unit inoperative. Thus the problems associated with the prior art doffer may be expressed in terms of the operating life of the doffer and the coordinated cotton picker spindles.
Yet another problem with prior art doffers is distortion of the backing plate which may cause the doffer to wobble during operation. The backing plate may be distorted by high pressures generated during the rubber molding process, or a distorted backing plate may be flattened during the rubber molding process.